This invention in general relates to the production of activated carbon. Particularly, this invention relates to a method for producing activated carbon with a high-added value from industrial waste carbon black such as that produced from waste-tire recycling industry or combustion electric power plant.
In recent years the already huge and ever growing number of waste tires and waste plastics has become an urgent and worldwide environmental pollution problem, probably next in importance only to the disposal of radioactive wastes. Presently in waste-rubber/waste-plastic recycling industry the usual practice is to have the wastes pulverized and then thrown into a sealed heat splitting decomposition furnace where at high temperature the pulverized wastes are decomposed and separated into fuel oil, fuel gas, carbonized substance and other residues like steel wire and so on. Special methods and techniques for this purpose have been disclosed in Japan Patent No. 51-18577 and No. 58-25384, U.S. Pat. No. 5,326,791, as well as Taiwan Patent No. 162283 and No. 221705. The fuel oil and fuel gas so produced are readily useful. As to the carbonized substance this solid matter may be pulverized and ground into carbon black powders or granulates for reuse in tire, rubber, or ink industry. Be that as it may, attention needs be drawn to the fact that nowadays the supply of carbon black has already exceeded the need, and due to the inferior quality of such carbon black recovered from waste tires and waste plastics there is practically no place for it in the market. Besides, more and more carbon black are daily coming out from combustion electric power plants and from all sorts of industrial furnaces that consume heavy oil, coal or natural gas, it is obvious that carbon black is more a threat to our environment than an inexpensive raw material for particular industries. To this problem a promising solution is to render such virtually useless carbon black into activated carbon which is an industrial commodity with high added value. At present, the activated carbon sold in the market, whether in the form of powder or granulate, is produced from carbonation and then activation of waste wood pieces, saw dusts, coconut shells, or all kinds of natural coal; to our knowledge, nothing of it comes from industrial waste carbon black. In a previous disclosure (U.S. Pat. No. 05,976,484) the inventors have presented a method as well as a device for recovering refined activated carbon from waste tires and the like: the present disclosure is a follow-up of their effort on the same topic.
A major object of this invention is to provide a method for producing activated carbon from carbon black, wherein industrial waste carbon black after preheating and steam activation processes is turned into activated carbon with a high-added value.
A further object of this invention is to provide a method for producing activated carbon from carbon black, wherein purified carbon black powder is subject to preheating and microwave heating, and then is delivered into a high-temperature activation furnace where it is activated under steam and carbon dioxide or nitrogen to form activated carbon.
A still further object of this invention is to-provide a method for producing activated carbon from carbon black, whereby the activation process is accomplished within a short time in a continuous working manner with the advantage of high productivity and low cost.